星系尺度致密性是否调控星云电子密度？基于DESI的跨尺度检验
Does galaxy-scale compactness regulate nebular electron density? A cross-scale test with DESI
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中文总结 AI 辅助
本研究利用DESI数据，在控制恒星质量与恒星形成率后，发现星系恒星面密度（致密性）与星云电子密度呈系统性正相关，首次提供受控群体级证据，表明星系尺度结构影响亚星系尺度电离气体状态。
中文摘要 AI 辅助
星云电子密度$n_e$示踪了小尺度H\\,{\sc ii}区和弥散电离结构中的电离气体，而星系恒星面密度$\Sigma_\star$则衡量kpc尺度上的致密性。这些量是否相关因此是一个跨尺度问题，而非几何恒等式。我们在控制恒星质量与恒星形成率（SFR）的相关效应后，检验星云电子密度是否随星系尺度恒星致密性系统性变化。我们使用DESI DR 1光谱，在$0.10<z<0.44$的AGN洁净恒星形成星系中检验这一跨尺度联系。我们将每个红移区间按$\Sigma_\star=M_\star/(2\pi R_e^2)$分为三分位。我们构建了一个对照样本，其中三个致密性三分位的$M_\star$分布相匹配，以及第二个样本，其中它们的联合$M_\star$--SFR分布相匹配，从而最小化这些相关星系属性的影响。对于每个致密性三分位，我们等权重叠加星系光谱，并使用叠加光谱测量该样本中星系的平均$n_e$。在所有红移区间中，平均$n_e$随恒星面密度增加而系统性增大。这是首个受控的群体级证据，表明kpc尺度星系恒星面密度（致密性）与亚星系尺度电离气体平均$n_e$之间存在相关性。在匹配$M_\star$和SFR后其持续性表明，更致密的恒星构型可能促进更高的气体压力和/或对电离气体的更强约束，将星系尺度结构与星云条件联系起来。
英文摘要
Nebular electron density, $n_e$, traces ionized gas in small-scale H\,{\sc ii} regions and diffuse ionized structures, whereas galaxy stellar surface density, $Σ_\star$, measures compactness on kpc scales. Whether these quantities are correlated is therefore a cross-scale question rather than a geometrical identity. We test whether nebular electron density varies systematically with galaxy-scale stellar compactness after controlling for the correlated effects of stellar mass and star-formation rate (SFR). We use DESI DR 1 spectra to test this cross-scale connection in AGN-clean star-forming galaxies at $0.10<z<0.44$. We divide each redshift interval into tertiles of $Σ_\star=M_\star/(2πR_e^2)$. We construct one controlled sample in which the $M_\star$ distributions are matched across the three compactness tertiles, and a second in which their joint $M_\star$--SFR distributions are matched, thereby minimizing the influence of these correlated galaxy properties. For each compactness tertile, we stack the galaxy spectra with equal weight and use the stacked spectrum to measure the average $n_e$ of the galaxies in that sample. The average $n_e$ increases systematically toward higher stellar surface density in all redshift intervals. This is the first controlled population-level evidence for a correlation between kpc-scale galaxy stellar surface density (compactness) and the average $n_e$ of ionized gas on subgalactic scales. Its persistence after matching both $M_\star$ and SFR suggests that a more compact stellar configuration may promote higher gas pressure and/or stronger confinement of ionized gas, linking galaxy-scale structure to nebular conditions.
发表机构
- University of Science and Technology of China（中国科学技术大学）
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